The next time you see a sagging power line, know that our researchers are working to make sure the stress on that line does not increase the stress in your life due to power outages, especially in sweltering summer heat.

More federal funding of $500,000 has been earmarked by the U.S. House of Representatives, with approval scheduled to go before the Senate, to support the Center for Energy Systems Research, led by Director and Mechanical Engineering Professor Sastry Munukutla. This is in addition to the $1 million appropriated for the current financial year. Researchers are looking to vastly improve current methods and create new methods to predict and prevent power outages caused by overstressed transmission lines.

"With air conditioners running all the time, the electric load on power lines is the highest in the summer," says Munukutla. "As the electric load starts to increase, there will be a point where the transmission system can no longer support the increased load due to voltage collapse."

This situation can be corrected by a technique known as relative power compensation (also known as VAR, for voltage ampere resistance), and Ghadir Radman, associate professor of Electrical and Computer Engineering, is working toward addressing the problem using state-of-the-art techniques.

Munukutla explains that the sag in a power line is due to the heat in the line, and heat is related to the electric load. The more the electric load increases, the more sagging occurs. If the sag exceeds a certain level, it can lead to additional electrical and mechanical problems that could eventually disrupt power transmission. Therefore, it is extremely important to monitor the sag in real time.

"There are simple measurement methods, but we need a more sophisticated state-of-the-art method," says Satish Mahajan, professor of Electrical and Computer Engineering, who is heading the project. "One idea we have is to use a global positioning system to measure the sag. Currently, helicopters are used to fly over and take data, but obviously this is a very dangerous method to use."

Whether it is a local power outage or a blackout such as the one that left millions in the dark in the Northeastern United States in 2003, common challenges have arisen in preventing small- and large-scale power interruptions. One is the increased demand, but another emerging issue is new operating patterns.

"Twenty or 30 years ago, power was generated and distributed by one power plant in an area," says Munukutla. "Now hospitals, manufacturing plants and other large facilities, even Wal-Marts, can and do generate their own power. All the predictive methods we have today do not take this distributed generation into consideration. We don't know what to expect and have to find a way to adapt our methods to the current situation."

Munukutla says TTU researchers will also pursue the study of system performance and control related to distributed generation.

This multi-year funded research is targeted at optimizing the power flow through high voltage transmission lines by collecting sag information online and judiciously choosing the location and type of VAR compensation.

"This research will not only benefit Tennesseans, but people across the nation who face everything from inconvenience to hardships because of power outages," says Munukutla.